Process heater system

ABSTRACT

A process heater system ( 10 ) for an industrial envelope ( 11 ) comprises a main combustion chamber ( 20 ), an afterburner ( 30 ), and an exhaust stack ( 40 ). Retrofitted heat-recovery piping ( 50 ) receives combustion gas downstream of the afterburner ( 30 ) and uses it as a heat source for the industrial envelope. When the industrial load in the main combustion chamber ( 20 ) is paint, powder coating, varnish, epoxy, grease and/or oil, the secondary materials burned in the afterburner  30  can be considered alternative fuel, not solid wastes.

RELATED APPLICATION

This application claims priority under 35 U.S.C. 119(e) to U.S. Provisional Patent Application No. 61/370,804 filed on Aug. 4, 2011. The entire disclosure of this provisional application is hereby incorporated by reference.

BACKGROUND

An industrial process heater can comprise a main combustion chamber, an afterburner, and an exhaust stack. The main combustion chamber volatizes an industrial load (e.g., dry paint, powder coating, varnish, epoxy, oil, and/or grease). A supplemental combustion chamber which is a first zone (or zone one) of the afterburner, completes the combustion of non-hazardous volatized organic material. Combustion gas passes from the supplemental combustion chamber to a second zone (or zone two) of the afterburner. The combustion gas dwells for at least half a second in the afterburner, and then passes to the exhaust stack for exhaust outside the envelope of the industrial facility.

SUMMARY

A system is provided wherein stack-exhaust heat is captured and transmitted for use as an energy source for the industrial envelope. For example, the stack-exhaust heat can be used to radiantly heat the envelope of the industrial facility. Alternatively, the recovered heat can be used to heat water or another liquid. In either or any event, material combusted in the afterburner is a recycled alternative fuel, not a solid waste.

DRAWINGS

FIG. 1 is a schematic side view of a process heater system for an industrial zone.

FIG. 2 is a schematic top view of the process heater system.

FIG. 3 is a schematic view of a radiant-heat pipe straightened to show temperature distribution along its length.

FIGS. 4-7 are sectional views of different regions of the radiant-heat pipe.

FIGS. 8 and 9 are each diagrams of heating control procedures.

FIG. 10 is a schematic view of a liquid-heating cycle for the process heater system.

DESCRIPTION

Referring now to the drawings, and initially to FIG. 1, a process heater system 10 for an industrial envelope 11 is shown. The system 10 comprises a main combustion chamber 20, an afterburner 30, an exhaust stack 40, and heat-recovery piping 50. As is explained in more detail below, the piping 50 captures heat normally lost through the exhaust stack 40 and converts it into heat for use within the industrial envelope 11.

The main combustion chamber 20 has a gas burner 21 and volatizes the industrial load. In other words, the industrial purpose of the process heater is performed in the main combustion chamber 20. This purpose can comprise, for example, heat cleaning fixtures, parts, and/or equipment to remove non-hazardous material that is not a solid waste.

The afterburner 30 comprises a supplemental combustion chamber 31 having its own gas burner 32 and in communication with the main combustion chamber 20. Often, as illustrated, the supplemental chamber 31 is within the same package perimeter as the main combustion chamber. The supplemental chamber 31 is considered the first zone of the afterburner 30 and its function is to complete the combustion of non-hazardous volatized organic material transported from the main chamber 20.

The afterburner 30 comprises a second zone 33 located downstream of the supplemental combustion chamber 31. This second zone 33 can be, as illustrated, outside the package perimeter of the chambers 20 and 31, and vertically aligned with the exhaust stack 40. The afterburner 30 can be sized so that combustion gas dwells therein for at least half a second. From the afterburner 30, combustion gas passes to the exhaust stack 40 for exhaust outside the industrial envelope 11.

The heat-recovery piping 50 can comprise a network of pipes which each include an adapter region 51, an inlet region 52, an intermediate region 53, and an outlet region 54. The adapter region 51 is connected to the exhaust stack 40 to receive combustion gas therefrom. An existing exhaust stack 40 can be retrofitted with the adapter region 51.

The heat-recovery piping 50 can project, turn, and extend to effectively cover the industrial envelope 11. For example, as is best seen by referring additionally to FIG. 2, four pipes can extend tangentially outward from the exhaust stack 40 at settings that are approximately 90° apart. That being said, in some facilities fewer pipes (e.g., a single pipe) or more pipes may be sufficient/necessary to accommodate the relevant industrial envelope 11.

The pipes 50 are preferably positioned close to the ceiling and horizontally oriented. For example, the pipes 50 can be hung about twelve to sixteen feet over the floor of the industrial envelope 11. Lower heights are possible, but may require shielding to prevent overheating of personnel. Higher heights are also possible, but may result in lost heat (e.g., about 1% per foot). The pipes 50 can be supported by beams, girders or joists. The piping 50 may also be gradually sloped downward (e.g., about ¼ inch per each ten feet length) to prevent water accumulation.

As is best seen by referring additionally to FIG. 3, combustion gas entering the pipe 50 will be at an extremely high temperature (e.g., at least 1000° F., at least 1100° F., at least 1200° F., at least 1300° F., at least 1400° F., about 1500° F. etc.). And preferably combustion gas exiting the pipe 50 will be at a much lower temperature (e.g., less than 800° F., less than 700° F., less than 600° F., less than 500° F., less than 400° F., about 300° F., etc.).

As shown in FIGS. 4-7, the radiant-heat-pipe regions 51-54 can each include a cylindrical housing 55 forming the gas passage. The housing 55 is made of material (e.g., radiant galvanized steel) which allows infrared heat to be emitted therefrom. The piping 50, and thus the housing 55, can have an OD dimension in the range of 3-5 inches (e.g., 4 inches). The heat-recovery piping 50 can also include roof-like reflectors 56 along its length to insure that any radiant heat directed upward will be reflected downward towards the desired heating area.

In the adapter region 51 and the inlet region 52, the heat-recovery piping 50 includes insulation 57 on its inside surface as shown in FIGS. 4-5. This insulation 57 is provided to lower the radiant heat emitted by the corresponding housing 51 in regions 51/52 and to help retain the intense heat for transportation to regions 53 and 54. The intermediate region 53 can include a turbulator 58 to spin the combustion gas along the interior surface of the pipe. The intermediate region 53 and the outlet region 54 can be without interior insulation.

Returning now back to FIG. 2, the process heater system 10 can additionally comprise tail piping 60 and an exhaust device 70. The tail piping 60 conveys the now cooler combustion gas to the exhaust device 70. To this end, it can comprise, as illustrated, a branch 61 connected to the outlet region 54 of each radiant-heat pipe 50 and a common branch 62 connecting each branch 61 to the exhaust device 70. The exhaust device 70 (e.g., a vacuum pump or exhaust fan), pulls fluid through the pipes 50/60 and into a safe region of the atmosphere outside the industrial envelope 11. Dampers 63 can be provided in each tail pipe 60 to monitor the flow rate of combustion gas therethrough. A damper 64 can be provided on the common branch 62 and a drain 65 (for accumulated moisture) can be provided upstream of the exhaust device 70.

As is shown in FIGS. 8 and 9, a controller 80 can receive input from a thermostat 12 and convey instructions to the exhaust device 70 and/or the dampers 63. If the industrial envelope 11 includes a conventional space heater 13 as shown in FIG. 9, the controller 80 can likewise control it.

The exhaust device 70 can be continuously run to provide the system 10 with a “self-sealing” feature insuring that combustion gas does not escape into the industrial envelope 11.

As is shown in FIG. 10, the process heater system 10 can additionally or alternatively incorporate a liquid-heating cycle 90 (e.g., a tank 91, a pump 92, inlet tube 93, heat exchanger 94, and outlet tube 95). With the cycle 90, the liquid is heated by the combustion gas passing through the heat-recovery piping 50 and stored in a tank 91. This liquid (e.g., water) can be used for locker room showers, industrial processing steps, or other applications requiring a heated fluid.

Thus, the system 10 is a process heater unit with an afterburner 30 and a heat recovery system (50, 60, 70, 80, 90). The material combusted in the afterburner 30 is fuel used to provide heat or other energy for the industrial envelope 11. This fuel material is recycled and legitimately used as an alternative fuel or ingredient. It can be produced and used for energy recovery from a non-hazardous valuable commodity secondary material with meaningful heating value and without contaminants significantly higher in concentration than traditional fuel. When the industrial load in the main combustion chamber 20 is paint, powder coating, varnish, epoxy, grease and/or oil, the secondary materials burned in the afterburner 30 are not solid wastes.

Although the process heater system 10, the main combustion chamber 20, the afterburner 30, the exhaust stack 40, and/or the heat-recovery elements (50, 60, 70, 80, 90) have been shown and described with respect to a certain embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings.

REFERENCE NUMBERS

10 process heater system

11 industrial envelope

12 thermostats

13 space-heating unit

20 main combustion chamber

21 main combustion burner

30 afterburner

31 supplemental combustion chamber

32 supplemental combustion burner

33 second zone of afterburner

40 exhaust stack

50 heat-recovery piping

51 adaptor region

52 inlet region

53 intermediate region

54 outlet region

55 housing

56 reflector roof

57 interior insulation sleeve

58 turbulator

60 tail piping

61 separate branches

62 common branch

63 dampers for separate branch

64 damper for common branch

65 moisture drain

70 exhaust device (vacuum pump)

80 controller

90 liquid-heating cycle

91 tank

92 pump

93 inlet tube

94 heat exchanger

95 outlet tube 

1. A process heater system (10) for an industrial envelope (11), comprising: a main combustion chamber (20) wherein an industrial load is combusted; an afterburner (30) comprising a supplemental combustion chamber (31) in communication with the main combustion chamber (20) and a second zone (33) in communication with the supplemental combustion chamber (31); an exhaust stack (40) receiving combustion gas from the second zone (33) of the afterburner (30) and exhausting it outside the industrial envelope (11); and heat-recovery piping (50) receiving combustion gas downstream of the second zone (33) the afterburner (30) and transmitting it for use within the industrial envelope (11), whereby material combusted in the afterburner (30) is fuel used to provide energy for the industrial envelope (11).
 2. A process heater system (10) as set forth in claim 1, wherein the afterburner (30) is sized so that combustion gas dwells therein for at least half a second.
 3. A process heater system (10) as set forth in claim 1, wherein the industrial load in the main combustion chamber (20) is paint, powder coating, varnish, epoxy, grease and/or oil.
 4. A process heater system (10) as set forth in claim 1, wherein the material combusted in the afterburner (30) has a meaningful heating value and is without contaminants significantly higher in concentration than traditional fuel.
 5. A process heater system (10) as set forth in claim 1, wherein the main combustion chamber (20) volatizes the industrial load.
 6. A process heater system (10) as set forth in claim 1, wherein the main combustion chamber (20) has a gas burner (21).
 7. A process heater system (10) as set forth in claim 1, wherein the industrial purpose of the main combustion chamber (20) is to heat clean fixtures, parts, and/or equipment to remove non-hazardous material.
 8. A process heater system (10) as set forth in claim 1, wherein the afterburner (30) comprises a supplemental combustion chamber (31).
 9. A process heater system (10) as set forth in claim 8, wherein the supplemental combustion chamber (31) has its own gas burner (32).
 10. A process heater system (10) as set forth in claim 8, wherein the supplemental combustion chamber (31) is in communication with the main combustion chamber (20).
 11. A process heater system (10) as set forth in claim 8, wherein the supplemental chamber (31) is in the same package perimeter as the main combustion chamber (20).
 12. A process heater system (10) as set forth in claim 8, wherein the supplemental combustion chamber (31) combusts non-hazardous volatized organic material transported from the main combustion chamber (20).
 13. A process heater system (10) as set forth in claim 1, wherein the afterburner (30) comprises a second zone (33).
 14. A process heater system (10) as set forth in claim 13, wherein the second zone (33) is located downstream of a/the supplemental combustion chamber (31).
 15. A process heater system (10) as set forth in claim 13, wherein the second zone (33) is outside of the package perimeter of the main combustion chamber (20).
 16. A process heater system (10) as set forth in claim 13, wherein the second zone (33) is vertically aligned with the exhaust stack (40).
 17. A process heater system (10) as set forth in claim 1, wherein the heat-recovery piping (50) projects, turns, and extends to effectively cover the industrial envelope (11).
 18. A process heater system (10) as set forth in claim 1, wherein four pipes extend tangentially outward from the exhaust stack (40) at settings that are approximately 90° apart and wherein each pipe (50) includes an adapter region (51) connected to the exhaust stack (40) to receive combustion gas therefrom.
 19. A process heater system (10) as set forth in claim 18, wherein the exhaust stack (40) is retrofitted with the adapter region(s) (51).
 20. A process heater system (10) as set forth in claim 18, wherein the exhaust stack (40) is manufactured to include the adapter region(s) (51). 